Generally, domestic hot water is supplied via a water heater appliance that is sized for the expected hot water draw. Insufficient hot water can strongly negatively affect the comfort of any occupants of the residence and lead to frustration and/or an expensive replacement of the appliance. However, excessive hot water capacity can lead to energy inefficiencies and poor performance. Examples of water heater appliances include traditional hot water heater tanks, ‘instant’ hot water heaters which are often called ‘tankless water heaters’, and indirect water heaters. Commonly, each of these water heater appliances are a compromise between water heater performance values such as: ‘peak draw’ performance; ‘continuous draw’ performance; ‘first draw’ performance; efficiency; operating cost; and initial cost.
Peak draw performance is a measure of how much hot water is available during peak demands. This is normally an increased amount over what the appliance can produce continuously (e.g., continuous draw performance) based on the amount of hot water the appliance is storing. When this peak demand is at the beginning of the hot water draw it is considered a “First Draw Performance”. A Peak Draw Value can be expressed as gallons per minute (GPM) at a specific temperature rise for a limited period of time. This temperature rise is a measure of the difference in temperature between the incoming water supplying the water heater appliance and the hot water supplied by the water heater appliance. After that time the temperature of the water delivered will drop.
While conventional water heater appliances attempt to create a good balance of water heater performance values, they typically fail to efficiently provide both good peak draw and continuous draw (or steady state) performance. Accordingly, there is a need in the art to improve the water heater appliance.